U.S. Pat. No. 6,110,617 discloses a flooded lead acid battery including a casing enclosing a plurality of cells having liquid electrolyte therein and a cover incorporating negative and positive terminals and having a plurality of vent holes. The vent holes are covered by at least one closure having a vent cavity therein, and a relatively rigid porous polytetrafluoroethylene disc having hydrophobic properties is sealed within the vent cavity.
U.S. Pat. No. 3,507,708 discloses a membrane made of a microporous piece of a perhalogenated aliphatic hydrocarbon, preferably polytetrafluoroethylene or polytrifluoromonochloroethylene, with respect to which the angle of wetting or contact of the liquid to be stopped is substantially greater than 90°. This membrane can form a part of a stopper for primary or secondary cells for preventing the escape of the liquid electrolyte from such cells, while permitting the escape of gases produced in the cells.
U.S. Pat. No. 5,348,570 discloses a venting mechanism that includes three members. A baffle is located within the bore of the second member. A Gortex film and wire mesh are retained within the bore of the third member by a rolled lip. The baffle and Gortex film act to maintain liquid on one side of the breather while allowing gases to freely pass there through.
U.S. Pat. No. 5,422,199 discloses a venting system for an electric storage battery that comprises a venting plug associated with each process hole. The venting plugs have a generally cylindrical side wall, a closed upper end, an open lower end, and a central cavity. A vent aperture is located in the side wall of the venting plug and is in gaseous communication with the manifold and the venting plug central cavity. A baffle is positioned within the venting plug central cavity between the vent aperture and the lower end of the venting plug. The baffle is adapted to allow the passage of gases and to retard the passage of electrolyte from the cell cavity through the venting plug central cavity.
U.S. Pat. No. 5,981,099 discloses a storage battery with a number of cells having an access port to each cell. Positioned in each access port is a valve. The valve generally includes a cap housing, a sealing O-ring, a flame arrester and a valve member.
U.S. Pat. No. 6,092,812 discloses a cover element for an opening in the body of a motor vehicle, such as a window or sunroof, that has a ventilation opening for air exchange between the interior and exterior of the vehicle. A permeable membrane permits passage of air but prevents an entry of water to the interior. The membrane is secured by a sealing ring.
U.S. Pat. No. 6,521,024 discloses a seal plate with a separate explosion preventing valve and a breather opening. A special breaking plate is employed in the explosion preventing valve opening.